JP7733809B2 - Medium conveying device, medium conveying method, and control program - Google Patents

Description

The present disclosure relates to a media conveying device, a media conveying method, and a control program, and in particular to a media conveying device, a media conveying method, and a control program that aligns the leading edge of a medium.

In media transport devices such as scanners that transport media to capture images, a function has been developed to align the leading edge of the media by rotating the transport roller that transports the media in the direction that returns the media for a predetermined period of time in order to correct the tilt of the transported media.

An image recording device has been disclosed that, if the registration sensor is OFF when image recording for one page of the preceding paper is complete, rotates the paper feed roller in the reverse direction to return the succeeding paper to the paper feed cassette (see Patent Document 1). When the registration sensor is ON, this image recording device rotates the paper feed roller forward by a predetermined amount, bringing the leading edge of the succeeding paper into contact with a pair of registration rollers and subjecting it to registration.

A sheet conveying device has been disclosed that temporarily stops a sheet at a registration position, which is the nip between a pair of pre-reading rollers just before the image reading position, and then resumes conveying the sheet (see Patent Document 2). This sheet conveying device controls the conveyance of the succeeding sheet so that it reaches the registration position after the preceding sheet has been discharged to the discharge section.

Japanese Patent Application Laid-Open No. 2007-90801 Japanese Patent Application Laid-Open No. 2021-52381

Media transport devices are required to properly align the leading edge of the media using transport rollers while suppressing increases in device costs.

The media conveying device, media conveying method, and control program of the embodiments aim to properly align the leading edge of the media using a conveying roller while suppressing increases in device costs.

A media transport device according to one aspect of the embodiment includes a feed roller for feeding a medium, a first transport roller positioned downstream of the feed roller in the media transport direction and rotating forward to transport the medium in the media transport direction, a second transport roller positioned downstream of the first transport roller in the media transport direction and rotating forward to transport the medium in the media transport direction, a motor for simultaneously driving the first transport roller and the second transport roller, a sensor positioned upstream of the first transport roller in the media transport direction, a determination unit that determines whether the trailing edge of the medium has passed the second transport roller, and a control unit that stops or rotates the first transport roller in the reverse direction and controls the feed roller to align the leading edge of the medium at the position of the first transport roller. When the leading edge of the first medium is detected by the sensor, and the determination unit determines that the trailing edge of a second medium preceding the first medium has passed the second transport roller, the control unit aligns the leading edge of the first medium.

A media transport method according to one aspect of the embodiment includes: feeding a medium using a feed roller; simultaneously driving a first transport roller, which is located downstream of the feed roller in the media transport direction and rotates forward to transport the medium in the media transport direction, and a second transport roller, which is located downstream of the first transport roller in the media transport direction and rotates forward to transport the medium in the media transport direction, using a motor; determining whether the trailing edge of the medium has passed the second transport roller; stopping or rotating the first transport roller in the reverse direction; and controlling the feed roller to align the leading edge of the medium at the position of the first transport roller; and, when the leading edge of the first medium is detected by a sensor located upstream of the first transport roller in the media transport direction, if it is determined that the trailing edge of a second medium preceding the first medium has passed the second transport roller, aligning the leading edge of the first medium.

A control program according to one aspect of the embodiment is a control program for a media transport device having a feed roller for feeding media, a first transport roller positioned downstream of the feed roller in the media transport direction and rotating forward to transport the media in the media transport direction, a second transport roller positioned downstream of the first transport roller in the media transport direction and rotating forward to transport the media in the media transport direction, a motor for simultaneously driving the first transport roller and the second transport roller, and a sensor positioned upstream of the first transport roller in the media transport direction. The control program determines whether the trailing edge of the media has passed the second transport roller, stops or rotates the first transport roller in the reverse direction, and controls the feed roller to align the leading edge of the media at the position of the first transport roller. During the alignment, if the sensor detects the leading edge of the first medium and it is determined that the trailing edge of a second medium preceding the first medium has passed the second transport roller, the control program aligns the leading edge of the first medium.

According to this embodiment, the media conveying device, media conveying method, and control program are able to properly align the leading edge of the media using the conveying roller while suppressing increases in device costs.

The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

1 is a perspective view showing a medium conveying device 100 according to an embodiment. 2 is a diagram for explaining a transport path inside the medium transport device 100. FIG. FIG. 10 is a schematic diagram for explaining a second medium sensor 114 and the like. 1 is a block diagram showing a schematic configuration of a medium conveying device 100. FIG. FIG. 2 is a diagram showing a schematic configuration of a storage device 140 and a processing circuit 150. 10 is a flowchart illustrating an example of the operation of a medium transport process. 10 is a flowchart illustrating an example of the operation of a medium transport process. 3A and 3B are schematic diagrams for explaining the positional relationship between a medium and each roller, etc. FIG. 10A and 10B are schematic diagrams for explaining alignment of the leading edge of a medium. 10 is a flowchart illustrating an example of the operation of a medium reading process. FIG. 10 is a diagram showing a schematic configuration of another processing circuit 250.

The following describes a media conveying device, a media conveying method, and a control program according to one aspect of the present disclosure, with reference to the accompanying drawings. However, please note that the technical scope of the present invention is not limited to these embodiments, but extends to the inventions set forth in the claims and their equivalents.

Figure 1 is a perspective view showing a media transport device 100 configured as an image scanner. The media transport device 100 transports and captures an image of a medium, which is an original document. The medium may be paper, thin paper, thick paper, a card, a booklet, or the like. The media transport device 100 may also be a facsimile, a copier, a multifunction printer (MFP, Multifunction Peripheral), or the like. Note that the transported medium may not be an original document but may be a print target, and the media transport device 100 may also be a printer, or the like.

The media transport device 100 comprises a lower housing 101, an upper housing 102, a loading tray 103, an ejection tray 104, an operation device 105, and a display device 106. In Figure 1, arrow A1 indicates the media transport direction, arrow A2 indicates the width direction perpendicular to the media transport direction, and arrow A3 indicates the height direction perpendicular to the media transport path. Hereinafter, "upstream" refers to the upstream side of the media transport direction A1, and "downstream" refers to the downstream side of the media transport direction A1.

The upper housing 102 is positioned to cover the top surface of the media conveying device 100 and is engaged with the lower housing 101 by a hinge so that it can be opened and closed when media becomes jammed or when cleaning the inside of the media conveying device 100, etc.

The loading tray 103 engages with the lower housing 101 and places media to be fed and transported on it. The ejection tray 104 engages with the upper housing 102 and places ejected media on it. Note that the ejection tray 104 may also engage with the lower housing 101.

The operation device 105 has input devices such as buttons and an interface circuit that acquires signals from the input devices, accepts input operations by the user, and outputs operation signals in response to the user's input operations. The display device 106 has a display such as a liquid crystal display, organic EL (Electro-Luminescence), etc., and an interface circuit that outputs image data to the display, and displays the image data on the display.

Figure 2 is a diagram illustrating the transport path inside the media transport device 100.

The transport path inside the media transport device 100 includes a first media sensor 111, a feed roller 112, a separation roller 113, a second media sensor 114, a third media sensor 115, a fourth media sensor 116, a first transport roller 117, a first driven roller 118, an imaging device 119, a fifth media sensor 120, a second transport roller 121, and a second driven roller 122, etc.

The number of each of the feed roller 112, separation roller 113, first conveying roller 117, first driven roller 118, second conveying roller 121 and/or second driven roller 122 is not limited to one, and may be multiple. In this case, the multiple feed rollers 112, separation rollers 113, first conveying roller 117, first driven roller 118, second conveying roller 121 and/or second driven roller 122 are arranged at intervals in the width direction A2, which is perpendicular to the medium conveying direction.

The upper surface of the lower housing 101 forms a lower guide 101a of the media transport path, and the lower surface of the upper housing 102 forms an upper guide 102a of the media transport path.

The first media sensor 111 is positioned upstream of the feed roller 112 and separation roller 113. The first media sensor 111 has a contact detection sensor and detects whether or not a medium is placed on the placement table 103. The first media sensor 111 generates and outputs a first media signal whose signal value changes depending on whether or not a medium is placed on the placement table 103. Note that the first media sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as an optical detection sensor, may be used as the first media sensor 111.

The feed roller 112 is provided in the lower housing 101. The feed roller 112 is rotatable in the media feed direction A4, and separates and feeds the media placed on the mounting table 103 sequentially from the bottom. The separation roller 113 is a so-called brake roller or retard roller, and is provided in the upper housing 102, and is arranged opposite the feed roller 112. The separation roller 113 is rotatable or stoppable in the direction A5 opposite the media feed direction. Alternatively, the feed roller 112 may be provided in the upper housing 102 and the separation roller 113 in the lower housing 101, and the feed roller 112 may feed the media placed on the mounting table 103 sequentially from the top.

The first conveying roller 117 and the first driven roller 118 are arranged facing each other downstream of the feed roller 112 and separation roller 113 in the media conveying direction A1. The first conveying roller 117 is provided in the upper housing 102 and conveys the media fed by the feed roller 112 and separation roller 113 to the imaging device 119. Note that the first conveying roller 117 may be provided in the lower housing 101 and the first driven roller 118 in the upper housing 102.

The first conveying roller 117 conveys the fed medium in the media conveying direction A1, i.e., downstream, by rotating in the forward direction A6, which applies a force to the medium toward the downstream side. Meanwhile, the first conveying roller 117 stops the advance of the leading edge of the fed medium and aligns the leading edge of the medium by stopping or rotating in the reverse direction A7, which applies a force to the medium toward the upstream side. In other words, by stopping or rotating in the reverse direction A7, the first conveying roller 117 functions as a registration roller that corrects the tilt of the leading edge of the fed medium. When the first conveying roller 117 rotates in the forward direction A6, the first driven roller 118 rotates in the forward direction A8, driven by the first conveying roller 117. On the other hand, when the first conveying roller 117 rotates in the reverse direction A7, the first driven roller 118 rotates in the reverse direction A9, driven by the first conveying roller 117.

The imaging device 119 is an example of an imaging unit, and is arranged downstream of the first transport roller 117 and upstream of the second transport roller 121 in the medium transport direction A1, and captures images of the medium transported by the first transport roller 117 and the first driven roller 118. The imaging device 119 includes a first imaging device 119a and a second imaging device 119b arranged opposite each other across the medium transport path.

The first imaging device 119a has a line sensor based on a CIS (Contact Image Sensor) of a 1:1 optical system type with CMOS (Complementary Metal Oxide Semiconductor) imaging elements arranged in a line in the main scanning direction. The first imaging device 119a also has a lens that forms an image on the imaging element and an A/D converter that amplifies and analog-to-digital (A/D) converts the electrical signal output from the imaging element. The first imaging device 119a images the surface of the transported medium under control of the processing circuit described below, generates an input image, and outputs it.

Similarly, the second imaging device 119b has a CIS line sensor with a 1x magnification optical system that has CMOS imaging elements arranged in a line in the main scanning direction. The second imaging device 119b also has a lens that forms an image on the imaging element, and an A/D converter that amplifies and analog-to-digital (A/D) converts the electrical signal output from the imaging element. The second imaging device 119b captures the back side of the medium being transported under control of the processing circuit described below, generates an input image, and outputs it.

The medium conveying device 100 may have only one of the first imaging device 119a and the second imaging device 119b, and may read only one side of the medium. Also, instead of a CIS line sensor with an equal-magnification optical system and a CMOS imaging element, a CIS line sensor with an equal-magnification optical system and a CCD (Charge Coupled Device) imaging element may be used. Also, a reduction optical system type line sensor with a CMOS or CCD imaging element may be used.

The second conveying roller 121 and the second driven roller 122 are arranged facing each other in the media conveying direction A1, downstream from the imaging device 119, i.e., downstream from the first conveying roller 117 and the first driven roller 118. The second conveying roller 121 is provided in the upper housing 102 and conveys the medium conveyed by the first conveying roller 117 and the first driven roller 118 further downstream and discharges it onto the discharge tray 104. Note that the second conveying roller 121 may be provided in the lower housing 101 and the second driven roller 122 may be provided in the upper housing 102.

The second conveying roller 121 conveys the fed medium in the medium conveying direction A1, i.e., downstream, by rotating in the forward direction A10, which applies a force to the medium toward the downstream side. When the second conveying roller 121 rotates in the forward direction A10, the second driven roller 122 rotates in the forward direction A11, following the second conveying roller 121.

Media placed on the mounting table 103 are transported between the lower guide 101a and the upper guide 102a in the media transport direction A1 as the feed roller 112 rotates in the media feed direction A4. The media transport device 100 has two feeding modes: a separation mode in which the media is separated while being fed, and a non-separation mode in which the media is fed without being separated. The feed mode is set by the user using the operation device 105 or an information processing device that communicates with the media transport device 100. When the feed mode is set to separation mode, the separation roller 113 rotates in the direction opposite the media feed direction A5 or stops. When multiple media are placed on the mounting table 103, the feed roller 112 and separation roller 113 function to separate only the media placed on the mounting table 103 that are in contact with the feed roller 112. This limits the transport of media other than the separated media (preventing double feeding). On the other hand, when the feeding mode is set to the non-separation mode, the separation roller 113 rotates in the medium feeding direction (the opposite direction to the arrow A5).

The medium is guided by the lower guide 101a and upper guide 102a and fed into the nip between the first conveyor roller 117 and the first driven roller 118. The first conveyor roller 117 and the first driven roller 118 rotate in the reverse directions A7 and A9, respectively, for a certain period of time, causing the leading edge of the medium to be held in the nip between the first conveyor roller 117 and the first driven roller 118. During this time, the medium is pushed out by the feed roller 112, and the leading edge of the medium is aligned. The first conveyor roller 117 and the first driven roller 118 then rotate in the forward directions A6 and A8, respectively, causing the medium to be fed between the first imaging device 119a and the second imaging device 119b. The medium scanned by the imaging device 119 is then ejected onto the ejection tray 104 by the second conveyor roller 121 and the second driven roller 122 rotating in the directions of arrows A10 and A11, respectively.

Also, as shown in Figure 2, the media conveying device 100 has a first motor 131, a second motor 132, and a third motor 133 as drive sources for each roller.

The first motor 131 is provided in the lower housing 101 and is connected to the feed roller 112 via the first transmission mechanism 131a to drive the feed roller 112. The first motor 131 generates a driving force to rotate the feed roller 112 and feed the medium in response to a control signal from the processing circuit. The first motor 131 may also be located in the upper housing 102.

The first transmission mechanism 131a includes one or more pulleys, belts, gears, etc. arranged between the first motor 131 and the shaft 112a, which is the rotation axis of the feed roller 112, and transmits the driving force generated by the first motor 131 to the feed roller 112.

The second motor 132 is provided in the upper housing 102 separately from the first motor 131, and is connected to the separation roller 113 via the second transmission mechanism 132a to drive the separation roller 113. The second motor 132 generates a driving force to rotate the separation roller 113 in response to a control signal from the processing circuit, causing the separation roller 113 to separate, feed, and transport the media. The second motor 132 may also be located in the lower housing 101.

The second transmission mechanism 132a includes one or more pulleys, belts, gears, etc., arranged between the second motor 132 and the shaft 113a, which is the rotation axis of the separation roller 113. The second transmission mechanism 132a transmits the driving force generated by the second motor 132 to the separation roller 113.

The medium conveying device 100 further includes a torque limiter 113b. The torque limiter 113b is provided between the second motor 132 and the separation roller 113. In the example shown in FIG. 2, the torque limiter 113b is disposed on the shaft 113a, which is the rotation axis of the separation roller 113. The torque limiter 113b determines the limit value of the torque applied to the separation roller 113. The limit value of the torque limiter 113b is set to a value such that the rotational force via the torque limiter 113b is cut off when there is one medium, and that the rotational force via the torque limiter 113b is transmitted when there are multiple media. As a result, when only one medium is being conveyed, the separation roller 113 does not rotate according to the driving force from the second motor 132, but instead follows the rotation of the feed roller 112. On the other hand, when multiple media are being transported, the separation roller 113 rotates in the direction A5 opposite the medium feeding direction to separate the media in contact with the feed roller 112 from other media, thereby preventing double feeding. At this time, the outer circumferential surface of the separation roller 113 may apply a force to the media in the direction A5 opposite the medium feeding direction while remaining stationary and not rotating in the direction A5 opposite the medium feeding direction.

The third motor 133 is an example of a motor. The third motor 133 is provided in the upper housing 102 separately from the first motor 131 and the second motor 132. The third motor 133 is connected to the first transport roller 117 and the second transport roller 121 via a third transmission mechanism 133a, and drives the first transport roller 117 and the second transport roller 121 simultaneously. The third motor 133 generates a driving force for rotating the first transport roller 117 and the second transport roller 121 in response to a control signal from the processing circuit, causing the first transport roller 117 and the second transport roller 121 to transport and eject the medium. The third motor 133 may also be arranged in the lower housing 101.

The third transmission mechanism 133a includes one or more pulleys, belts, gears, etc. arranged between the third motor 133 and the shaft 117a, which is the rotation axis of the first conveying roller 117, and the shaft 121a, which is the rotation axis of the second conveying roller 121. The third transmission mechanism 133a transmits the driving force generated by the third motor 133 to the first conveying roller 117 and the second conveying roller 121.

In this way, in the medium conveying device 100, a common third motor 133 is used as the motor for driving the first conveying roller 117 and the motor for driving the second conveying roller 121. This allows the medium conveying device 100 to reduce the number of motors, thereby reducing the cost, size, and weight of the device.

The first driven roller 118 is a driven roller that rotates in accordance with the first conveyor roller 117, and the second driven roller 122 is a driven roller that rotates in accordance with the second conveyor roller 121. The first driven roller 118 and/or the second driven roller 122 may be configured to be driven by driving force from the third motor 133. In this case, one or more gears are further provided between the shaft 117a of the first conveyor roller 117 and the shaft 118a, which is the rotation axis of the first driven roller 118, and/or between the shaft 121a of the second conveyor roller 121 and the shaft 122a, which is the rotation axis of the second driven roller 122. The third transmission mechanism 133a further transmits the driving force generated by the third motor 133 to the first driven roller 118 and/or the second driven roller 122.

Figure 3 is a schematic diagram for explaining the second media sensor 114, the third media sensor 115, the fourth media sensor 116, and the fifth media sensor 120. Figure 3 is a schematic diagram of the lower housing 101 viewed from above with the upper housing 102 open.

In the example shown in Figure 3, two of each of the feed roller 112, separation roller 113, first conveying roller 117, first driven roller 118, second conveying roller 121 and second driven roller 122 are provided.

The second media sensor 114 and the third media sensor 115 are arranged downstream of the feed roller 112 and upstream of the first conveying roller 117 in the media conveying direction A1, i.e., upstream of the imaging device 119. In particular, the second media sensor 114 and the third media sensor 115 are arranged upstream of the fourth media sensor 116. Furthermore, the second media sensor 114 and the third media sensor 115 are arranged side by side with a gap between them outside the fourth media sensor 116 in the width direction A2 (towards the side wall W of the media conveying path), in particular outside the two feed rollers 112. The second media sensor 114 and the third media sensor 115 each detect media conveyed to their respective positions.

The second media sensor 114 includes a light emitter and a light receiver located on one side of the media transport path, and a light guide located opposite the light emitter and light receiver across the media transport path. The light emitter is an LED (Light Emitting Diode) or the like, and emits light toward the media transport path. The light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide. When a medium is present in a position opposite the second media sensor 114, the light emitted from the light emitter is blocked by the medium, and the light receiver does not detect the light emitted from the light emitter. The second media sensor 114 generates and outputs a second media signal whose signal value changes depending on whether a medium is present or not at the second media sensor 114, based on the intensity of the light received by the light receiver.

The third media sensor 115 includes a light emitter and a light receiver located on one side of the media transport path, and a light guide located opposite the light emitter and light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. The light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide. When a medium is present in a position opposite the third media sensor 115, the light emitted from the light emitter is blocked by the medium, and the light receiver does not detect the light emitted from the light emitter. The third media sensor 115 generates and outputs a third media signal, the signal value of which changes depending on whether a medium is present or not at the third media sensor 115, based on the intensity of the light received by the light receiver.

The fourth media sensor 116 is an example of a sensor. The fourth media sensor 116 is positioned downstream of the feed roller 112 and upstream of the first transport roller 117 in the media transport direction A1, i.e., upstream of the imaging device 119. The fourth media sensor 116 is also positioned in the center in the width direction A2, particularly between the two feed rollers 112, the two first transport rollers 117, and/or the two second transport rollers 121. The fourth media sensor 116 is preferably positioned in a central position between the two first transport rollers 117 in the width direction A2. The fourth media sensor 116 detects media transported to its position.

The fourth media sensor 116 includes a light emitter and a light receiver located on one side of the media transport path, and a light guide located opposite the light emitter and light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. The light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide. The fourth media sensor 116 generates and outputs a fourth media signal, the signal value of which changes depending on whether a medium is present or absent at the position of the fourth media sensor 116, based on the intensity of the light received by the light receiver.

The fifth media sensor 120 is an example of the second sensor. The fifth media sensor 120 is arranged downstream of the imaging device 119 and upstream of the second transport roller 121 in the media transport direction A1. The fifth media sensor 120 is also arranged in the center in the width direction A2, particularly between the two feed rollers 112, the two first transport rollers 117, and/or the two second transport rollers 121. The fifth media sensor 120 is preferably arranged in a central position between the two second transport rollers 121 in the width direction A2. The fifth media sensor 120 detects media transported to its arrangement position.

The fifth media sensor 120 includes a light emitter and a light receiver provided on one side of the media transport path, and a light guide tube provided opposite the light emitter and light receiver across the media transport path. The light emitter is an LED or the like, and emits light toward the media transport path. Meanwhile, the light receiver is a photodiode or the like, and receives the light emitted by the light emitter and guided by the light guide tube. Based on the intensity of the light received by the light receiver, the fifth media sensor 120 generates and outputs a fifth media signal, the signal value of which changes depending on whether a media is present or not at the position of the fifth media sensor 120. The fifth media signal is an example of an output signal from the second sensor.

In addition, in the second media sensor 114, the third media sensor 115, the fourth media sensor 116, and/or the fifth media sensor 120, a reflective member such as a mirror may be used instead of a light guide tube. Furthermore, in the second media sensor 114, the third media sensor 115, the fourth media sensor 116, and/or the fifth media sensor 120, the light emitter and the light receiver may be arranged opposite each other across the media transport path. Furthermore, the second media sensor 114, the third media sensor 115, the fourth media sensor 116, and/or the fifth media sensor 120 may detect the presence of media using a contact detection sensor or the like that passes a predetermined current when the media is in contact or when the media is not in contact.

Figure 4 is a block diagram showing the general configuration of the media conveying device 100.

In addition to the above-mentioned configuration, the media conveying device 100 further includes an interface device 134, a memory device 140, a processing circuit 150, etc.

The interface device 134 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown) (e.g., a personal computer, a mobile information terminal, etc.) to send and receive input images and various information. Alternatively, instead of the interface device 134, a communication unit may be used that has an antenna for sending and receiving wireless signals and a wireless communication interface device for sending and receiving signals via a wireless communication line in accordance with a predetermined communication protocol. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network). The communication unit may also have a wired communication interface device for sending and receiving signals via a wired communication line in accordance with a communication protocol such as a wired LAN.

The storage device 140 may include a memory device such as RAM (Random Access Memory) or ROM (Read Only Memory), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or optical disk. The storage device 140 also stores computer programs, databases, tables, etc. used for various processes of the medium conveying device 100. Computer programs may be installed into the storage device 140 from a computer-readable portable recording medium using a known setup program, etc. Portable recording media include, for example, a CD-ROM (compact disc read only memory) or a DVD-ROM (digital versatile disc read only memory).

The processing circuit 150 operates based on a program stored in advance in the storage device 140. The processing circuit is, for example, a CPU (Central Processing Unit). The processing circuit 150 may also be a DSP (digital signal processor), an LSI (large scale integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like.

The processing circuit 150 is connected to the operation device 105, display device 106, first medium sensor 111, second medium sensor 114, third medium sensor 115, fourth medium sensor 116, imaging device 119, fifth medium sensor 120, first motor 131, second motor 132, third motor 133, interface device 134, and storage device 140, and controls each of these components. Based on the medium signals received from each media sensor, the processing circuit 150 controls the drive of each motor and the imaging of the imaging device 119. The processing circuit 150 acquires an input image from the imaging device 119 and transmits it to the information processing device via the interface device 134. The processing circuit 150 also aligns the leading edge of the medium being transported based on the medium signals received from each media sensor.

Figure 5 is a diagram showing the general configuration of the memory device 140 and processing circuit 150.

As shown in FIG. 5, the storage device 140 stores a control program 141, a judgment program 142, etc. Each of these programs is a functional module implemented by software running on a processor. The processing circuit 150 reads each program stored in the storage device 140 and operates in accordance with the read program. As a result, the processing circuit 150 functions as a control unit 151 and a judgment unit 152.

Figures 6 and 7 are flowcharts showing an example of the operation of the media conveying process of the media conveying device 100.

Below, an example of the operation of the media conveying process of the media conveying device 100 will be described with reference to the flowcharts shown in Figures 6 and 7. Note that the operation flow described below is executed mainly by the processing circuit 150 in cooperation with each element of the media conveying device 100 based on a program stored in advance in the storage device 140.

First, the control unit 151 waits until the user inputs an instruction to read a medium using the operation device 105 or the information processing device, and an operation signal instructing the reading of a medium is received from the operation device 105 or the interface device 134 (step S101).

Next, the control unit 151 acquires a first medium signal from the first medium sensor 111 and determines whether or not a medium is placed on the placement table 103 based on the acquired first medium signal (step S102). If no medium is placed on the placement table 103, the control unit 151 ends the series of steps.

On the other hand, if a medium is placed on the mounting table 103, the control unit 151 drives the first motor 131 and the second motor 132 to rotate the feed roller 112 and the separation roller 113 and feed the medium (step S103). The control unit 151 rotates the feed roller 112 in the medium feed direction A4 and rotates the separation roller 113 in the direction A5 opposite to the medium feed direction.

Next, the determination unit 152 acquires the second medium signal, the third medium signal, the fourth medium signal, and the fifth medium signal from the second medium sensor 114, the third medium sensor 115, the fourth medium sensor 116, and the fifth medium sensor 120, respectively. The determination unit 152 associates each acquired medium signal with the acquisition time and stores them in the storage device 140 (step S104).

Next, the control unit 151 determines whether the leading edge of the medium being fed has passed the position of the fourth medium sensor 116 based on the fourth medium signal (step S105). The control unit 151 determines that the leading edge of the medium has passed the position of the fourth medium sensor 116 when the signal value of the fourth medium signal changes from a value indicating that the medium is not present to a value indicating that the medium is present. If the leading edge of the medium being fed has not yet passed the position of the fourth medium sensor 116, the control unit 151 returns to step S104 and repeats the processes of steps S104 to S105.

On the other hand, when the leading edge of the medium being fed passes the position of the fourth medium sensor 116, the determination unit 152 detects the tilt of the trailing edge of the preceding medium that was fed immediately before the medium being fed and that precedes the medium being fed (step S106). The medium being fed, i.e., the following medium that follows the preceding medium, is an example of the first medium. The preceding medium is an example of the second medium. Note that if the medium currently being fed is the first medium fed among the media loaded together on the loading tray 103, there is no preceding medium, and the control unit 151 proceeds to step S108 without executing the processes of steps S106 and S107.

The determination unit 152 detects the tilt of the trailing edge of the preceding medium based on, for example, the second medium signal and the third medium signal stored in the storage device 140. The determination unit 152 detects the most recent time at which the signal value of the second medium signal acquired to date changed from a value indicating the presence of a medium to a value indicating the absence of a medium as the time at which the trailing edge of the preceding medium passed the position of the second medium sensor 114. Similarly, the determination unit 152 detects the most recent time at which the signal value of the third medium signal acquired to date changed from a value indicating the presence of a medium to a value indicating the absence of a medium as the time at which the trailing edge of the preceding medium passed the position of the third medium sensor 115. The determination unit 152 calculates the tilt θ1 of the trailing edge of the preceding medium using the following equation (1):
θ1=tan ^-1 (T1×V1/W0) (1)
Here, T1 is the time difference between the time when the trailing edge of the preceding medium passes the position of the second medium sensor 114 and the time when it passes the position of the third medium sensor 115. V1 is the transport speed of the preceding medium. That is, (T1 x V1) represents the difference in distance in the medium transport direction A1 of the trailing edge of the preceding medium between the placement positions of the second medium sensor 114 and the third medium sensor 115. W0 is the distance between the second medium sensor 114 and the third medium sensor 115 in the width direction A2.

The determination unit 152 may also use known image processing techniques to detect the tilt of the trailing edge of the preceding medium from an input image of the preceding medium. In this case, the determination unit 152 calculates the absolute value of the difference in gradation values between the pixels on either side of each pixel in the vertical direction (sub-scanning direction) for each vertical line extending in the vertical direction (sub-scanning direction) in the input image of the preceding medium. The determination unit 152 detects pixels in each vertical line whose adjacent gradation value exceeds a gradation threshold as edge pixels, and detects the lowest edge pixel among the detected edge pixels as the bottom edge pixel. The gradation value may be a brightness value or a color value (R value, G value, or B value). The gradation threshold is set, for example, to a brightness value difference (e.g., 20) that allows a person to visually distinguish differences in brightness in an image.

The determination unit 152 may calculate the absolute value of the difference in gradation values between two pixels that are a predetermined distance away from each pixel in the input image in the vertical direction as the adjacent difference value. The determination unit 152 may also detect edge pixels by comparing the gradation value of each pixel in the input image with a threshold value. For example, if the gradation value of a specific pixel is less than the threshold value and the gradation value of a pixel that is vertically adjacent to the specific pixel or a pixel that is a predetermined distance away from the specific pixel is greater than or equal to the threshold value, the determination unit 152 detects the specific pixel as an edge pixel.

The determination unit 152 detects straight lines from the bottom edge pixels using the least squares method. The determination unit 152 may also detect straight lines using a Hough transform. The determination unit 152 detects the inclination of the detected straight line relative to a horizontal line extending horizontally (main scanning direction) in the input image as the inclination of the trailing edge of the preceding medium.

Next, the determination unit 152 determines whether the trailing end of the preceding medium has passed the second conveying roller 121 (step S107).

The determination unit 152 determines whether the signal value of the fifth media signal has changed from a value (OFF) indicating the absence of media to a value (ON) indicating the presence of media after the feed of the preceding media has started. If the signal value of the fifth media signal has not changed from OFF to ON after the feed of the preceding media has started, the determination unit 152 determines that the leading edge of the preceding media has not yet passed the position of the fifth media sensor 120 and that the trailing edge of the preceding media has not yet passed the second conveyance roller 121. If the signal value of the fifth media signal has changed from OFF to ON after the feed of the preceding media has started, the determination unit 152 further determines whether the signal value of the fifth media signal has changed back to OFF. If the signal value of the fifth media signal has not changed back to OFF, the determination unit 152 determines that the trailing edge of the preceding media has not yet passed the position of the fifth media sensor 120 and that the trailing edge of the preceding media has not yet passed the second conveyance roller 121.

On the other hand, if the signal value of the fifth medium signal changes from OFF to ON and then changes back to OFF after feeding of the preceding medium begins, the determination unit 152 determines that the trailing end of the preceding medium has passed the position of the fifth medium sensor 120. In this case, the determination unit 152 calculates the first distance traveled by the trailing end of the preceding medium from the position of the fifth medium sensor 120.

Figure 8 is a schematic diagram for explaining the positional relationship between the transported medium and each roller and each media sensor. Figure 8 is a schematic diagram of the lower housing 101 viewed from above with the upper housing 102 open.

Figure 8 shows an example in which the leading medium M1 and the trailing medium M2 are transported at an angle so that the left side leads and the right side lags.

The determination unit 152 calculates a first distance Y1 that the trailing edge of the preceding medium has moved from the position of the fifth medium sensor 120 at position P1 of the outer edge in the width direction A2 of the nip portion between the second conveyance roller 121 and the second driven roller 122 on the side where the progress of the preceding medium is delayed, using the following equation (2). Hereinafter, the nip portion between the second conveyance roller 121 and the second driven roller 122 may be referred to as the discharge portion.
Y1=Y0-(W1/2)×tanθ1 (2)
Here, Y0 is the distance that the trailing edge of the preceding medium moves in the media conveyance direction A1 from the position of the fifth media sensor 120 at position P0 in the width direction A2 where the fifth media sensor 120 is located. Y0 is calculated by multiplying the elapsed time from when the trailing edge of the preceding medium passed the position of the fifth media sensor 120 to the present by the conveyance speed V1 of the preceding medium. W1 is the distance between the outer ends of the nip portions of the two sets of second conveyance rollers 121 and second driven rollers 122 in the width direction A2.

If the first distance Y1 is greater than the distance L1 between the fifth media sensor 120 in the media transport direction A1 and a predetermined position C1 of the discharge section, the determination unit 152 determines that the trailing edge of the preceding medium has passed the second transport roller 121. The predetermined position C1 is set, for example, to the center position of the discharge section. Alternatively, the predetermined position C1 may be set to the position where the discharge section intersects with a line passing through the center of rotation of the second transport roller 121 and the center of rotation of the second driven roller 122. Alternatively, the predetermined position C1 may be set to the downstream end position of the discharge section. On the other hand, if the first distance Y1 is equal to or less than the distance L1, the determination unit 152 determines that the trailing edge of the preceding medium has not passed the second transport roller 121.

In this way, the determination unit 152 determines whether the trailing edge of the medium has passed the second conveyor roller 121 based on the detected tilt of the trailing edge of the medium and the fifth medium signal from the fifth medium sensor 120. This allows the determination unit 152 to determine with high accuracy whether the trailing edge of the medium has passed the second conveyor roller 121.

The determination unit 152 may determine whether the trailing end of the medium has passed the second conveying roller 121 without taking into account the inclination of the trailing end of the medium. In this case, the determination unit 152 calculates the distance Y0 that the trailing end of the preceding medium has moved in the medium conveying direction A1 from the position of the fifth media sensor 120 at position P1 in the width direction A2 where the fifth media sensor 120 is located as the first distance Y1.

The determination unit 152 may also determine that the trailing end of the medium has passed the second conveying roller 121 if the distance Y0 is greater than a predetermined distance threshold. The distance threshold is set to a distance at which the trailing end of the medium, conveyed at an angle at the maximum angle allowed by the medium conveying device 100, does not come into contact with the discharge unit.

In addition, the determination unit 152 may use the fourth media signal from the fourth media sensor 116 instead of the fifth media signal from the fifth media sensor 120 to determine whether the rear end of the medium has passed the second conveying roller 121.

If the determination unit 152 determines that the trailing edge of the preceding medium has passed the second conveying roller 121, the control unit 151 controls the third motor 133 to stop the first conveying roller 117 or rotate it in the reverse direction A7 (step S108). If the first conveying roller 117 rotates in the reverse direction A7, the first driven roller 118 rotates in the reverse direction A9, driven by the first conveying roller 117. On the other hand, if the first conveying roller 117 stops, the first driven roller 118 stops, driven by the first conveying roller 117. Note that if the leading edge of the medium is aligned by stopping the first conveying roller 117, and the first conveying roller 117 is currently stopped, step S108 may be omitted.

Next, the control unit 151 waits until a predetermined time has elapsed and aligns the leading edge of the medium at the position of the first conveying roller 117 (step S109). The predetermined time is set to the maximum or average value of the time required for the medium to be stopped by the first conveying roller 117 and the first driven roller 118 and for the tilt of the medium to be corrected (eliminated) in an experiment in which various types of medium were fed at various tilt angles.

Figure 9 is a schematic diagram to explain the alignment of the leading edge of the medium.

In the example shown in FIG. 9, multiple media M3 to M6 are placed together on the placement table 103. As shown in FIG. 9, of the media M3 to M6 placed on the placement table 103, only medium M3, which is in contact with the feed roller 112, is separated and fed, reaching the nip between the first conveying roller 117 and the first driven roller 118. At this time, the first conveying roller 117 and the first driven roller 118 stop or rotate in the reverse directions A7 and A9, and the progress of the leading edge of medium M3 is blocked by the first conveying roller 117 and the first driven roller 118. Meanwhile, in step S103, the feed roller 112 is controlled to rotate in the medium feed direction A4, and as the feed roller 112 continues to push medium M3 downstream, medium M3 is pushed downstream while bending upward. As a result, when the medium M3 is fed at an angle relative to the width direction A2, the leading edge of the medium M3 is positioned along the width direction A2 at the nip portion between the first conveying roller 117 and the first driven roller 118.

In this way, the control unit 151 stops the first transport roller 117 or rotates it in the reverse direction A7 for a predetermined time, and controls the feed roller 112 to rotate in the medium feed direction A4, thereby aligning the leading edge of the medium at the position of the first transport roller 117. This allows the control unit 151 to effectively correct the skew of the medium when the medium is being transported at an angle.

In particular, when the fifth media sensor 120 detects the leading edge of the following media, if the determination unit 152 determines that the trailing edge of the preceding media has passed the second transport roller 121, the control unit 151 aligns the leading edge of the following media. As described above, in the media conveying device 100, the third motor 133 is used as both the motor for driving the first transport roller 117 and the motor for driving the second transport roller 121. Therefore, when the control unit 151 stops or rotates the first transport roller 117 in the reverse direction A7, the second transport roller 121 also stops or rotates in the reverse direction A7. By aligning the leading edge of the following media when the trailing edge of the preceding media has passed the second transport roller 121, the control unit 151 can align the leading edge of the media without impeding the progress of the preceding media. Therefore, the media conveying device 100 can properly align the leading edges of the media while smoothly conveying multiple media.

Next, the control unit 151 controls the third motor 133 to rotate the first conveying roller 117 and the second conveying roller 121 in the forward directions A6 and A10 (step S110). At this time, the first driven roller 118 and the second driven roller 122 rotate in the forward directions A8 and A11, driven by the first conveying roller 117 and the second conveying roller 121, respectively. As a result, the first conveying roller 117, the first driven roller 118, the second conveying roller 121, and the second driven roller 122 convey the medium (subsequent medium) being fed after alignment toward the downstream side. The control unit 151 then proceeds to step S121.

On the other hand, if the determination unit 152 determines in step S107 that the trailing end of the preceding medium has not passed the second conveying roller 121, the control unit 151 detects the inclination of the leading end of the following medium being fed (step S111).

The control unit 151 detects the tilt of the leading edge of the following medium based on, for example, the second medium signal and the third medium signal stored in the storage device 140. The control unit 151 detects the most recent time at which the signal value of the second medium signal acquired to date changed from a value indicating the absence of a medium to a value indicating the presence of a medium as the time at which the leading edge of the following medium passed the position of the second medium sensor 114. Similarly, the control unit 151 detects the most recent time at which the signal value of the third medium signal acquired to date changed from a value indicating the absence of a medium to a value indicating the presence of a medium as the time at which the leading edge of the following medium passed the position of the third medium sensor 115. The control unit 151 calculates the tilt θ2 of the leading edge of the following medium using the following equation (3):
θ2=tan ^-1 (T2×V2/W0) (3)
Here, T2 is the time difference between the time when the leading edge of the succeeding medium passes the position of the second medium sensor 114 and the time when it passes the position of the third medium sensor 115. V2 is the transport speed of the succeeding medium. In other words, (T2 x V2) represents the difference in distance in the medium transport direction A1 of the leading edge of the succeeding medium between the position of the second medium sensor 114 and the position of the third medium sensor 115.

Next, the control unit 151 determines whether the leading edge of the subsequent medium has reached the first conveying roller 117 (step S112).

The control unit 151 calculates a second distance that the leading edge of the following medium has moved from the position of the fourth medium sensor 116. The control unit 151 calculates a second distance Y2 that the leading edge of the following medium has moved from the position of the fifth medium sensor 120 at position P2, the outer edge in the width direction A2, of the nip portion between the first conveyance roller 117 and the first driven roller 118 on the side on which the following medium is advancing, using the following equation (4):
Y2=(W2/2)×tanθ2 (4)
Here, as shown in FIG. 8, W2 is the distance between the outer ends of the nip portions of the two pairs of first conveying rollers 117 and first driven rollers 118 in the width direction A2.

When the second distance Y2 is greater than the distance L2 between the fourth media sensor 116 in the media transport direction A1 and a predetermined position C2 of the transport unit, the control unit 151 determines that the leading edge of the following medium has reached the first transport roller 117. The predetermined position C2 is set, for example, to the center position of the transport unit. Alternatively, the predetermined position C1 may be set to the position where the transport unit intersects with a line passing through the center of rotation of the first transport roller 117 and the center of rotation of the first driven roller 118. Alternatively, the predetermined position C1 may be set to the upstream end position of the transport unit. On the other hand, when the second distance Y2 is equal to or less than the distance L2, the control unit 151 determines that the leading edge of the following medium has not reached the first transport roller 117.

In this way, the control unit 151 determines whether the leading edge of the medium has reached the first conveyor roller 117 based on the detected tilt of the leading edge of the medium and the fourth medium signal from the fourth medium sensor 116. This allows the control unit 151 to determine with high accuracy whether the leading edge of the medium has reached the first conveyor roller 117.

In addition, the control unit 151 may determine that the leading edge of the medium has not reached the first conveying roller 117 when the leading edge of the medium passes the position of the fourth media sensor 116, without taking into account the inclination of the leading edge of the medium.

The control unit 151 may also determine whether the leading edge of the medium has reached the first conveying roller 117 based on whether a first time or more has elapsed since the start of feeding the medium, without using the fourth medium signal from the fourth medium sensor 116. The first time is set to the time required for the medium to move from the feeding roller 112 to the first conveying roller 117.

If it is determined that the leading edge of the following medium has not reached the first conveyor roller 117, the control unit 151 controls the first motor 131 to stop the feed roller 112 (step S113). If a preceding medium is present, in steps S110, S118, or S120, the first conveyor roller 117, first driven roller 118, second conveyor roller 121, and second driven roller 122 are controlled to rotate in the forward directions A6, A8, A10, and A11. However, because the leading edge of the following medium has not reached the first conveyor roller 117, the following medium stops in front of the first conveyor roller 117 due to the stop of the feed roller 112, and does not move downstream.

Next, the determination unit 152 waits until the trailing edge of the preceding medium passes the second transport roller 121 (step S114). The determination unit 152 determines whether the trailing edge of the preceding medium has passed the second transport roller 121, similar to the processing in step S107. At this point, the trailing edge of the preceding medium has moved the first distance Y1 calculated in step S107 from the position of the fifth media sensor 120 at position P1, the outer edge of the transport section on the side where progress is delayed. Therefore, the determination unit 152 waits for the time required for the preceding medium to move the distance obtained by subtracting the first distance Y1 from the distance L1 between the fifth media sensor 120 and the specified position C1 of the transport section. When the preceding medium has passed the second transport roller 121, it is discharged to the discharge tray 104.

In this way, when the fifth media sensor 120 detects the leading edge of the following medium, if the determination unit 152 has not determined that the trailing edge of the preceding medium has passed the second conveyance roller 121, the control unit 151 controls the feed roller 112 to stop feeding the preceding medium until the trailing edge of the preceding medium has passed the second conveyance roller 121. This allows the media conveyance device 100 to reliably separate the preceding medium from the second conveyance roller 121 before the following medium reaches the first conveyance roller 117. Therefore, when the following medium reaches the first conveyance roller 117, the media conveyance device 100 can properly align the leading edge of the following medium using the first conveyance roller 117 without interfering with the conveyance of the medium by the second conveyance roller 121, which operates in conjunction with the first conveyance roller 117.

Next, the control unit 151 re-drives the first motor 131 to rotate the feed roller 112 again and resume feeding the subsequent medium (step S115). This causes the subsequent medium to advance toward the first conveying roller 117.

Next, the control unit 151 controls the third motor 133 to stop the first conveying roller 117 or rotate it in the reverse direction A7 (step S116), similar to the processing in step S108. As described above, when the control unit 151 stops the first conveying roller 117 or rotates it in the reverse direction A7, the second conveying roller 121 also stops or rotates in the reverse direction A7. However, because the preceding medium has already passed the second conveying roller 121 in step S114, the progress of the preceding medium is not obstructed.

Next, the control unit 151 waits until a predetermined time has elapsed, similar to the processing in step S109, and then aligns the leading edge of the medium at the position of the first conveying roller 117 (step S117).

In this way, when the determination unit 152 determines that the trailing edge of the preceding medium has passed the second conveyance roller 121, the control unit 151 controls the feed roller 112 to resume feeding the following medium and align the leading edge of the following medium. This allows the medium conveyance device 100 to properly guide the following medium to the position of the first conveyance roller 117 after the preceding medium has separated from the second conveyance roller 121, and properly align the leading edge of the following medium using the first conveyance roller 117.

Furthermore, the control unit 151 performs alignment of the leading edge of the following medium when the determination unit 152 determines that the trailing edge of the preceding medium has passed the second conveyance roller 121 after the leading edge of the following medium is detected by the fifth media sensor 120 but before the leading edge of the following medium reaches the first conveyance roller 117. This allows the medium conveyance device 100 to perform alignment of the leading edge of the following medium even if the trailing edge of the preceding medium has not yet passed the second conveyance roller 121 at the time the leading edge of the following medium passes the position of the fifth media sensor 120. Therefore, the medium conveyance device 100 can increase the frequency of performing media alignment and correct media skew more frequently.

Next, the control unit 151 controls the third motor 133 to rotate the first conveying roller 117 and the second conveying roller 121 in the forward directions A6 and A10 (step S118), similar to the processing in step S110. The control unit 151 then proceeds to step S121.

On the other hand, if it is determined in step S112 that the leading edge of the subsequent medium has reached the first conveying roller 117, the control unit 151 decides not to align the leading edge of the subsequent medium (step S119).

If the leading edge of the following medium has already reached the first transport roller 117 before the trailing edge of the preceding medium passes the second transport roller 121, the second transport roller 121 and the first transport roller 117 are in contact with the preceding medium and the following medium, respectively. Therefore, if the control unit 151 rotates the second transport roller 121 in the forward direction A10, the following medium will move further downstream along with the preceding medium, making it difficult for the first transport roller 117 to align the leading edge of the following medium. On the other hand, if the control unit 151 stops the first transport roller 117, it will be unable to move the preceding medium downstream. Therefore, in this case, the control unit 151 can prevent media transport from being delayed by continuing the media transport without aligning the leading edge of the following medium.

The processing of step S112 may be omitted, and the control unit 151 may decide not to align the leading edge of the subsequent medium regardless of whether the leading edge of the subsequent medium has reached the first conveying roller 117. In other words, when the leading edge of the subsequent medium is detected by the fifth media sensor 120, if the determination unit 152 has not determined that the rear end of the preceding medium has passed the second conveying roller 121, the control unit 151 will not align the leading edge of the subsequent medium. As a result, if it is difficult to align the leading edge of the subsequent medium, the control unit 151 can continue to transport the medium appropriately without aligning the leading edge of the subsequent medium.

Next, the control unit 151 controls the third motor 133 to rotate the first conveying roller 117 and the second conveying roller 121 in the forward directions A6 and A10, similar to the processing of step S110 (step S120).

Next, the control unit 151 determines whether or not a medium remains on the mounting table 103 based on the first medium signal received from the first medium sensor 111 (step S121). If a medium remains on the mounting table 103, the control unit 151 returns to step S104 and repeats steps S104 to S121.

On the other hand, if no media remain on the mounting table 103, the control unit 151 waits until the trailing end of the medium being transported (the subsequent medium) passes the second transport roller 121 (step S122). The control unit 151 periodically acquires a fifth medium signal from the fifth medium sensor 120, and determines that the trailing end of the medium has passed the position of the fifth medium sensor 120 when the signal value of the fifth medium signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium. The control unit 151 determines that the trailing end of the medium has passed the second transport roller 121 when a second time has elapsed since the trailing end of the medium passed the position of the fifth medium sensor 120. The second time is set to the time required for the medium to move from the position of the fifth medium sensor 120 to the second transport roller 121 plus a margin.

Next, the control unit 151 controls the first motor 131, the second motor 132, and the third motor 133 to stop the separation roller 113, the first conveying roller 117, the first driven roller 118, the second conveying roller 121, and/or the second driven roller 122 (step S123). This completes the series of steps for the control unit 151.

In addition, if the processing of step S112 is omitted and it is determined in step S107 that the trailing end of the preceding medium has not passed the second conveying roller 121, the control unit 151 may always perform the processing of steps S113 to S118.

Furthermore, as described above, when multiple media are being transported, the separation roller 113 rotates in the direction A5 opposite the media feeding direction to separate the media in contact with the feed roller 112 from the other media. Therefore, media following the medium being fed are not fed until the trailing edge of the medium being fed passes the nip between the feed roller 112 and the separation roller 113. However, the control unit 151 may control the first motor 131 to stop the feed roller 112 after rotating the first transport roller 117 and the second transport roller 121 in steps S110, S118, or S120. In this case, when the trailing edge of the medium passes the position of the second media sensor 114, the third media sensor 115, or the fourth media sensor 116, the control unit 151 re-drives the first motor 131 to re-rotate the feed roller 112 and resume feeding the subsequent medium. This allows the medium conveying device 100 to further reduce the occurrence of double feeding of media.

Figure 10 is a flowchart showing an example of the operation of the media reading process of the media conveying device 100.

Below, an example of the operation of the media reading process of the media conveying device 100 will be described with reference to the flowchart shown in Figure 10. Note that the flow of the operation described below is executed mainly by the processing circuit 150 in cooperation with each element of the media conveying device 100 based on a program stored in advance in the storage device 140. The flowchart shown in Figure 10 is executed in parallel with the media conveying process while it is being executed.

First, the control unit 151 waits until the leading edge of the medium passes the position of the fourth medium sensor 116 (step S201). The control unit 151 periodically acquires a fourth medium signal from the fourth medium sensor 116, and determines that the leading edge of the medium has passed the position of the fourth medium sensor 116 when the signal value of the fourth medium signal changes from a value indicating the presence of a medium to a value indicating the absence of a medium.

Next, the control unit 151 causes the imaging device 119 to start imaging the medium (step S202).

Next, the control unit 151 waits until the trailing edge of the medium passes the imaging position of the imaging device 119 (step S203). The control unit 151 periodically acquires a fifth medium signal from the fifth medium sensor 120 and determines that the trailing edge of the medium has passed the position of the fifth medium sensor 120 when the signal value of the fifth medium signal changes from a value indicating the presence of the medium to a value indicating the absence of the medium. The control unit 151 determines that the trailing edge of the medium has passed the imaging position when the trailing edge of the medium passes the position of the fifth medium sensor 120. The control unit 151 may use the fourth medium signal from the fourth medium sensor 116 instead of the fifth medium signal from the fifth medium sensor 120 to determine whether the trailing edge of the medium has passed the imaging position. In this case, the control unit 151 determines that the trailing edge of the medium has passed the imaging position when a third time has elapsed since the trailing edge of the medium passed the position of the fourth medium sensor 116. The third time is set to the time required for the medium to move from the position of the fourth medium sensor 116 to the imaging position plus a margin.

Next, the control unit 151 acquires an input image from the imaging device 119 and outputs the acquired input image by transmitting it to the information processing device via the interface device 134 (step S204). Next, the control unit 151 returns the process to step S201, and thereafter repeats the processes of steps S201 to S204 while the medium transport process is being executed.

As described above in detail, the medium conveying device 100 drives the first conveying roller 117 and the second conveying roller 121 with the same third motor 133. The medium conveying device 100 aligns the leading edge of the following medium when the trailing edge of the preceding medium passes the second conveying roller 121 before the leading edge of the following medium reaches the first conveying roller 117. This enables the medium conveying device 100 to properly align the leading edge of the medium using the first conveying roller 117 while suppressing increases in device costs. Furthermore, the medium conveying device 100 can properly align the leading edge of the medium using the first conveying roller 117 while suppressing increases in device size and weight.

When the first transport roller 117, which aligns the leading edge of the media, and the second transport roller 121, which ejects the media, are driven by a common motor, the two media being fed consecutively must be spaced far enough apart to rotate each roller in any direction at any timing. However, increasing the distance between the media increases the time required for the media transport process. The media transport device 100 feeds media so that the distance between the media when aligning the leading edges is the same as the distance between the media when not aligning the leading edges, and performs leading edge alignment when there is no problem with doing so. This allows the media transport device 100 to properly align the leading edges of the media using the first transport roller 117 while minimizing the increase in the time required for the media transport process.

The time required to separate and feed media varies depending on factors such as the type of media being fed and the load on the fed media (the amount of media stacked on the loading tray 103). Therefore, the distance between two consecutively fed media varies depending on factors such as the type of media being fed and the load on the fed media. The media transport device 100 determines whether to align the leading edge of the media based on the distance between the fed media and the preceding media when the media passes the position of the fourth media sensor 116, which is located upstream of the first transport roller 117 that aligns the leading edge of the media. This allows the media transport device 100 to accurately determine whether the leading edge of the media can be aligned without interfering with the transport of the preceding media, enabling the first transport roller 117 to properly align the leading edge of the media.

Figure 11 is a diagram showing the schematic configuration of a processing circuit 250 in a medium conveying device according to another embodiment. The processing circuit 250 is used in place of the processing circuit 150, and performs media reading processing, etc. in place of the processing circuit 150. The processing circuit 250 includes a control circuit 251 and a determination circuit 252, etc. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, etc.

The control circuit 251 is an example of a control unit and has the same functions as the control unit 151. The control circuit 251 receives an operation signal from the operation device 105 or the interface device 134. The control circuit 251 also receives a first medium signal, a fourth medium signal, and a fifth medium signal from the first medium sensor 111, the fourth medium sensor 116, and the fifth medium sensor 120, respectively, and receives the determination result of the medium position from the determination circuit 252. The control circuit 251 controls the first motor 131, the second motor 132, and the third motor 133 based on the received information, and also acquires an input image from the imaging device 119 and outputs it to the interface device 134.

The judgment circuit 252 is an example of a judgment unit and has the same function as the judgment unit 152. The judgment circuit 252 receives a second medium signal, a third medium signal, a fourth medium signal, and a fifth medium signal from the second medium sensor 114, the third medium sensor 115, the fourth medium sensor 116, and the fifth medium sensor 120, respectively. The judgment circuit 252 determines the position of the transported medium based on each received signal and outputs the judgment result to the control circuit 251.

As described above in detail, even when using the processing circuit 250, the media conveying device is able to properly align the leading edge of the media using the first conveying roller 117 while suppressing increases in device costs.

100 Media conveying device, 112 Feeding roller, 116 Fourth media sensor, 117 First conveying roller, 120 Fifth media sensor, 121 Second conveying roller, 133 Third motor, 151 Control unit, 152 Determination unit

Claims (9)

a feed roller for feeding the medium;
a first transport roller disposed downstream of the feed roller in a medium transport direction and configured to rotate in a forward direction to transport the medium in the medium transport direction;
a second transport roller disposed downstream of the first transport roller in the medium transport direction and configured to rotate in a forward direction to transport the medium in the medium transport direction;
a motor for simultaneously driving the first conveying roller and the second conveying roller;
a sensor disposed upstream of the first transport roller in the medium transport direction;
a determination unit that determines whether the trailing edge of the medium has passed the second conveyance roller;
a control unit that stops the first conveying roller or rotates it in a reverse direction and controls the feed roller to align the leading edge of the medium at the position of the first conveying roller,
the control unit performs position alignment of the leading edge of the first medium if the determination unit determines that the trailing edge of the second medium preceding the first medium has passed the second conveyance roller when the leading edge of the first medium is detected by the sensor;
A medium transport device characterized by: A medium conveying device as described in claim 1, wherein the control unit does not perform alignment of the leading edge of the first medium if the judgment unit does not determine that the trailing edge of the second medium has passed the second conveying roller when the leading edge of the first medium is detected by the sensor. The control unit performs alignment of the leading edge of the first medium when the determination unit determines that the trailing edge of the second medium has passed the second conveying roller after the leading edge of the first medium is detected by the sensor and before the leading edge of the first medium reaches the first conveying roller. The control unit
Detects the tilt of the media's leading edge
The medium transport device according to claim 3 , wherein whether or not the leading edge of the medium has reached the first transport roller is determined based on the detected tilt and an output signal from the sensor. The control unit of the media transport device described in claim 1 controls the feed roller to stop feeding of the first medium until the trailing end of the second medium passes the second transport roller when the sensor detects the leading edge of the first medium and the determination unit has not determined that the trailing end of the second medium has passed the second transport roller. A medium transport device as described in claim 5, wherein when the determination unit determines that the trailing edge of the second medium has passed the second transport roller, the control unit controls the feed roller to resume feeding of the first medium and align the leading edge of the first medium. a second sensor disposed upstream of the second transport roller in the medium transport direction;
The determination unit
Detects the tilt of the rear edge of the media
7. A medium transport device according to claim 1, wherein the device determines whether the trailing edge of the medium has passed the second transport roller based on the detected tilt and the output signal from the second sensor. A feed roller feeds the medium.
a motor simultaneously drives a first transport roller that is disposed downstream of the feed roller in the medium transport direction and that rotates in a forward direction to transport the medium in the medium transport direction, and a second transport roller that is disposed downstream of the first transport roller in the medium transport direction and that rotates in a forward direction to transport the medium in the medium transport direction;
determining whether the trailing edge of the medium has passed the second conveyance roller;
and stopping the first transport roller or rotating it in a reverse direction and controlling the feed roller to align the leading edge of the medium at the position of the first transport roller;
When the leading edge of the first medium is detected by a sensor disposed upstream of the first transport roller in the medium transport direction, if it is determined that the trailing edge of the second medium preceding the first medium has passed the second transport roller, the leading edge of the first medium is aligned.
A medium transport method comprising: a first transport roller disposed downstream of the feed roller in the medium transport direction and configured to transport the medium in the medium transport direction by rotating in a forward direction; a second transport roller disposed downstream of the first transport roller in the medium transport direction and configured to transport the medium in the medium transport direction by rotating in a forward direction; a motor for simultaneously driving the first transport roller and the second transport roller; and a sensor disposed upstream of the first transport roller in the medium transport direction,
determining whether the trailing edge of the medium has passed the second conveyance roller;
causing the medium transport device to stop or rotate the first transport roller in a reverse direction and control the feed roller to align the leading edge of the medium at the position of the first transport roller;
When the leading edge of the first medium is detected by the sensor during the alignment, if it is determined that the trailing edge of the second medium preceding the first medium has passed the second conveyance roller, alignment of the leading edge of the first medium is performed.
A control program comprising: